Classification and evolution 4.3 Flashcards
Why do humans classify living things?
- for our convenience
- makes the study of living things more manageable
- makes it easier to identify organisms
- helps us see the relationships between species
How many levels does the current system of classification use?
8 taxonomic levels
What are the 8 taxonomic levels called?
- domain
- kingdom
- phylum
- class
- order
- family
- genus
- species
What are the three domains?
- archaea
- eubacteria
- eukaryotae
What are the 5 main kingdoms?
- plantae
- animalia
- fungi
- protoctista
- prokaryotes
What is the phylum classification?
It is the major subdivision of the kingdom and contains all the groups of organisms that have the same body plan
What is the class classification?
A group of organisms tha all poses the same general traits (same number of legs)
What is the order classification?
A subdivision of class using additional info about the organisms (class mammal divided into order carnivora or order herbivora)
What is the family classification?
A group of closely related gena (withing order carnivora, dog and cat family)
What is the genus classification?
A group of closely related species
What is the species classification?
The basic unit of classification, all members show variation but are all essentially the same
What is classification?
The process of placing living things into groups
What happens as you desend to the lower taxonomic groups?
It becomes increasingly difficult to separate closely related species accurately and a very detailed description of the species is needed
What is the binomial naming system?
A system that uses the genus name and yje species name to avoid confusion when naming organisms
What does binomial mean?
Two names
Who divised the binomial system?
Carl linnaeus
Why does using common names not work well?
- different common names are used in different countries
- translation of languages may give different names
- same organisms have completely different common names in different parts of one country
- same common name might be used for different species in other parts of the world
What is a species?
A group of organisms that can freely interbreed to produce fertile offspring
What is the phylogenetic definition of a species?
A group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry and genetics
What are the characersitics of prokaryota?
What are the characteristics of protoctista?
What are the characteristics of fungi?
What are the characteristics of plantae?
What are the characteristics of animalia?
What is convergent evolution?
When two unrelated species adapt in similar ways
How does biological molecules help with classification?
They help determin how closely related one species is to another due to unique differences in large biological molecules which have changed due to evolution
What is cytochrome c?
A protein used in respiration that all living organisms that respire contain
Explain how biological molecules show how closely related species are to eachother
Two organisms with similar molecules will be closely related as they have not evolved separately for long and the other way round
Explain how cytochrom c shows the relationships between species
Cytochrome c is not identical in every species and the sequence of amino acids can be compared, the more differences between the sequence the less closely related the species are
Explain how DNA shows how closely related species are
By comparing DNA sequences, the more similar the sequence in a part of the DNA the more closely related the species
Which is probably the most accurate way to demonstrate how closely related species are?
Comparing DNA sequences
Who suggested the three domain system?
Carl Woese
What kingdom was divided into bacteria and archaea?
Prokaryota
What is phylogeny?
The study of the evolutionary relationships between organisms
What are the characteristics of artificial classification?
- based on few characteristics
- does not reflect any evolutionary relationships
- provides limited information
- is stable
What is artificial classification?
A form of classification that groups things in a way that is easy to remember or easy to find a particular object
What are the characteristics of natural classification?
- uses many characteristics
- reflects evolutionary relationships
- provides lots of useful information
- may change with advancing knowledge
What is natural classification?
A form of classification that involves detailed study of the individuals in a species and reflects real relationships betweeen the groups
What does a branched point mean on the evolutionary tree?
A common ancestor
What does it mean if two organisms have a recent common ancestor?
The two organisms are closely related
What is natural selection?
The term used to explain how features of the environment apply a selective force on the reproduction of individuals in a population
What did Charles darwin do?
He proposed a mechanism for the process of evolution (natural selection)
Who was Alfred Russel Wallace?
Another naturalist who came to the same conclusion as Darwin
What were the 4 observations that Darwin made?
- Offspring generally appear similar to their parents
- No two individuals are identical
- Organisms have the ability to produce a large number of offspring
- populations in nature tend to remain fairly stable in size
What did Darwin find out that fossils showed?
- in the past the world was inhabited by species that were different from those present today
- old species have died out and new species have arisen
- the new species that have appeared are often similar to the older ones found in the same place
What evidence is there for evolution?
- fossil evidence
- biological molecules
How does biological molecules provide evidence for evolution?
Closely related species will have identical or similar biological molecules and in distant species the biological molecules are likely to differ more (shown in DNA and cytochrome c)
What is continuous variation?
Variation where there are two extremes and a full range of values in between (height)
How should you present the data for continuous variation?
Histogram
What is discontinuous variation?
Where there are distinct categories and nothing in between (gender)
How should you present the data for discontinuous cariation?
Bar chart
Whats is environmental variation?
Variation caused by response to environmental factors such as light intensity (an overfed pet will become obese)
What is genetic variation?
Variation caused by possesing a different combination of alleles (The combination of alleles that we inherit is not the same as that in any other living thing)
What is interspecific variation?
The differences between species
What is intraspecific variation?
The variation between members of the same species (eye colour)
What is variation?
The presence of variety, the differences between individuals
What are some of the combined effects of genetic and environmental variation?
- humans have become taller as a result of a better diet but you are unlikely to grow tall if your family is short
- not all genes are active at any one time
- changes in the environment can also directly affect which genes are active
What is an adaptation?
A characteristic that enhances survival in the habitat
What is an anatomical adaptation?
Structural features (marram grass has curled leaves)
What is a behavioural adaptation?
The ways the behaviour is modified for survival (marram grass rolls leaves more when in a water shortage)
What is a physiological adaptation?
Affect the way the processes work (marram grass’ guard cells opening and closing the stomata)
What can a well adapted organism do?
- find enough foor or photosynthesise well
- find enough water
- gather enough nutrients
- defend itself from predators and disease
- respond to changes in the environment
- have sufficient energy for successful reproduction
- surviv the physical conditions of its environment
What is convergent evolution?
When unrelated species living in similar habitats evolve to have similar adaptations
Explain natural selection
An individual that has a characteristic which helps it survive in its environment is more likely to live long enough to reproduce
How does natural selection work?
- mutations create alleles
- this creates genetic intraspecific variation
- once variety exists and resources are scarce the environment can select the characteristics that give an advantage
- there is a selection pressure
- individual with advantageous characteristics will survive and reproduce
- and pass on the advantageous characteristics (inheritance)
- The next generation will have a higher proportion of those characteristics
- overtime the organism will become adapted to its environment
What is standard deviation?
A measure of the spread around the mean
What is a student’s t-test?
A test used to compare two means
What is spearman’s rank test?
A test done to measure the strength and direction of association between two continuous pieces of data
How do you conclude a T test?
- state the null hypothesis so there is no significant difference between the data sets
- calculate the t statistic using the t-test formula
- calculate degrees of freedom (n1 + n2 - 2)
- compare the statistic with the critical value
What does it mean if the t test is over the critical value?
- reject the null hypothesis
- the means are significanly different
What does it mean if the t test is below the critical value?
- accept the null hypothesis
- there is no significant difference between the means
- any difference is due to chance
How do you conclude a spearmans rank test?
- rank the raw data from smallest to largest
- find the difference in the ranks
- square the rank differences
- sum up all the squared rank differences
- put the values into the formula
- critical values table will use sapmle size rather than degrees of freedom
